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Common code for integration of Tiles for different templating technologies.
There is a newer version: 3.0.8
/*
 * $Id: InsertDefinitionModel.java 1058106 2011-01-12 12:22:58Z apetrelli $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.tiles.template;

import java.io.IOException;

import org.apache.tiles.Attribute;
import org.apache.tiles.AttributeContext;
import org.apache.tiles.TilesContainer;
import org.apache.tiles.access.TilesAccess;
import org.apache.tiles.autotag.core.runtime.ModelBody;
import org.apache.tiles.autotag.core.runtime.annotation.Parameter;
import org.apache.tiles.request.Request;

/**
 * 
 * Insert a definition.
 * 
 * 
 * Insert a definition with the possibility to override and specify parameters
 * (called attributes). A definition can be seen as a (partially or totally)
 * filled template that can override or complete attribute values.
 * <tiles:insertDefinition> allows to define these attributes
 * and pass them to the inserted jsp page, called template. Attributes are
 * defined using nested tag <tiles:putAttribute> or
 * <tiles:putListAttribute>.
 * 
 * 
 * You must specify name tag attribute, for inserting a definition
 * from definitions factory.
 * 
 * 
 * Example : 
 * 
 *
 *  * <code>
 *           <tiles:insertDefinition name=".my.tiles.defininition flush="true">
 *              <tiles:putAttribute name="title" value="My first page" />
 *              <tiles:putAttribute name="header" value="/common/header.jsp" />
 *              <tiles:putAttribute name="footer" value="/common/footer.jsp" />
 *              <tiles:putAttribute name="menu" value="/basic/menu.jsp" />
 *              <tiles:putAttribute name="body" value="/basic/helloBody.jsp" />
 *           </tiles:insertDefinition>
 *         </code>
 * 
 *
 * @version $Rev: 1058106 $ $Date: 2011-01-12 13:22:58 +0100 (Wed, 12 Jan 2011) $
 * @since 2.2.0
 */
public class InsertDefinitionModel {

    /**
     * Executes the operation.
     * @param definitionName The name of the definition to render.
     * @param template If specified, this template will be used instead of the
     * one used by the definition.
     * @param templateType The type of the template attribute.
     * @param templateExpression The expression to evaluate to get the value of the template.
     * @param role A comma-separated list of roles. If present, the definition
     * will be rendered only if the current user belongs to one of the roles.
     * @param preparer The preparer to use to invoke before the definition is
     * rendered. If specified, it overrides the preparer specified in the
     * definition itself.
     * @param flush If true, the response will be flushed after the insert.
     * @param request The request.
     * @param modelBody The body.
     * @throws IOException If something goes wrong.
     * @since 2.2.0
     */
    public void execute(
            @Parameter(name = "name", required = true) String definitionName,
            String template, String templateType, String templateExpression,
            String role, String preparer, boolean flush, Request request, ModelBody modelBody)
            throws IOException {
        TilesContainer container = TilesAccess.getCurrentContainer(request);
        container.startContext(request);
        modelBody.evaluateWithoutWriting();
        container = TilesAccess.getCurrentContainer(request);
        renderDefinition(container, definitionName, template, templateType,
                templateExpression, role, preparer, flush, request);
    }

    /**
     * Renders a definition.
     *
     * @param container The container to use.
     * @param definitionName The name of the definition to render.
     * @param template If specified, this template will be used instead of the
     * one used by the definition.
     * @param templateType The type of the template attribute.
     * @param templateExpression The expression to evaluate to get the value of the template.
     * @param role A comma-separated list of roles. If present, the definition
     * will be rendered only if the current user belongs to one of the roles.
     * @param preparer The preparer to use to invoke before the definition is
     * rendered. If specified, it overrides the preparer specified in the
     * definition itself.
     * @param flush If true, the response will be flushed after the insert.
     * @param request The request.
     * @throws IOException If something goes wrong.
     */
    private void renderDefinition(TilesContainer container,
            String definitionName, String template, String templateType,
            String templateExpression, String role, String preparer,
            boolean flush, Request request) throws IOException {
        try {
            AttributeContext attributeContext = container
                    .getAttributeContext(request);
            Attribute templateAttribute = Attribute.createTemplateAttribute(template,
                    templateExpression, templateType, role);
            attributeContext.setPreparer(preparer);
            attributeContext.setTemplateAttribute(templateAttribute);
            container.render(definitionName, request);
            if (flush) {
                request.getWriter().flush();
            }
        } finally {
            container.endContext(request);
        }
    }
}